A tree is subjected to large and small wounds due to an artificial factor such as pruning and transplanting, a meteorological factor such as typhoon and heavy snow, disease and insect pest, and the like.
A small wound on a large tree is generally healed by a self defense function of the tree.
However, when the wound on the tree is deep and large, the natural healing does not work well, and hence if it is left uncared, a woody tissue is decayed due to invasion of various germs through the wound, leading to development of a large cavity. This may threat the health of the tree, spoil the beauty, and cause an unexpected considerable damage on life and property from breakage of the tree in the vicinity of the cavity due to strong wind or the like.
For this reason, when a cavity is developed on a tree, a surgery is immediately performed on the tree to prevent a further decay of the cavity.
In such a conventional tree surgery method, a decomposed tissue in the cavity is removed with a sharp tool, before residual mycelium, spore, and harmful insects are removed by sterilization and insecticidal treatment. Thereafter, a preservative is applied, and the cavity is filled with urethane foam. Lastly, a surface treatment is performed by coating an epoxy resin.
However, the above tree surgery method is not effective from the aesthetic aspect due to a difference in colors between the tree and the artificial tree bark filled in the cavity. In addition, when exposed continuously to direct sunlight, as shown in FIG. 1(a), the artificial tree bark formed of the epoxy resin is cracked, oxidized, or degenerated, failing to serve as the tree bark, and hence as shown in FIG. 1(b), the urethane foam filled in the cavity is oxidized and degenerated, causing a decay of the cavity again.